Number reference
42 explained.
42: forty-two, composite; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- forty-two
- Classification
- composite
- Factors
- 1, 2, 3, 6, 7, 14, 21, 42
- Prime factorization
- 2 × 3 × 7
- Square root
- 6.480741
- Cube root
- 3.476027
- Binary
- 101010
- Octal
- 52
- Hexadecimal
- 2A
- Roman numeral
- XLII
- Digit sum
- 6
- Digital root
- 6
What makes 42 notable
- Factor structure. 42 breaks down into 3 distinct primes (2, 3, 7) and has 8 divisors in total, so it can be split into equal whole-number groups 6 ways beyond 1 and itself.
42 in everyday use
Forty-two is "the Answer to the Ultimate Question of Life, the Universe, and Everything" in Douglas Adams's The Hitchhiker's Guide to the Galaxy — a joke answer that became one of the most recognised numbers in popular culture.
Nearby numbers
How to read this page
The factor list shows every way 42 splits into equal whole-number groups — 8 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 42 for contexts that do not use decimal.
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